Pump displacement and drilling speed are 2 pivotal parameters in HDD. The matching state of pump displacement and drilling speed will affect the borehole quality and the construction progress, but there is no mature academic system to obtain them, for little research has been done in China, these parameters usually are estimated with experience in construction. In this article, mathematical analysis method is used with the consideration on the influence of drilled cuttings amount, calculating model of optimization of pump displacement and drilling speed is established combining with testing data for verification. It is proved by practice that this model is according with field construction.